Laxatives, Stool Softeners, and Prokinetic Agents

Constipation is a symptom with various etiologies and can be associated with many factors that contribute to its presentation.^[1]Primary constipation may be characterized by normal^[2]or slow intestinal transit or may be caused by an anatomical issue (eg, pelvic flow dysfunction). Secondary constipation is associated with endocrine or metabolic disorders (eg, hypercalcemia, hypothyroidism, pregnancy, diabetes mellitus), neurologic disorders (stroke, Parkinson disease, multiple sclerosis), connective tissue disorders (eg, scleroderma, amyloidosis), and eating disorders.^{[3, 4]}

Commonly identified medications that may contribute to constipation include antidepressants, iron, bismuth, anticholinergics, opioids, antacids, calcium channel blockers, nonsteroidal anti-inflammatory drugs (NSAIDs), sympathomimetics, and antipsychotics (typical or atypical). Long-term use of cholestyramine or stimulant laxatives may lead to a dilated atonic laxative colon, resulting in constipation and the presumed need for more laxatives.

The choice of laxative for treatment or prevention of constipation depends on the etiology. Medications to treat constipation include bulk-forming agents, lubricant laxatives, stool softeners, stimulant laxatives, osmotic laxatives, saline laxatives, and prokinetic agents.^{[3, 5, 4]}

Bulk-producing laxatives

These agents contain soluble fiber that absorbs water within the intestine. This promotes intestinal peristalsis. Bulk-forming agents are used for long-term prophylaxis, treatment of constipation, or both in patients without anatomic outlet obstruction. Bulk-producing laxatives include the following:

Lubricant laxatives

Lubricant laxatives are used for acute or subacute management of constipation. They lubricate the intestine and facilitate passage of stool by decreasing water absorption from the intestine. Lubricant laxatives include the following:

Stool softeners

Emollient stool softeners are used for prophylaxis against constipation in acute and subacute settings (eg, postoperative opioid-induced constipation).

Docusate is a surfactant laxative; it reduces tension of oil-water interface of the stool and enhances incorporation of water and fat into the stool, resulting in a softer stool

Stimulant laxatives

Stimulant laxatives include the following:

Bisacodyl or bisacodyl rectal - Stimulates peristalsis potentially by stimulating the colonic intramural neuronal plexus; alters water and electrolyte secretion, resulting in net intestinal fluid accumulation and laxation; provokes defecation within 24 hours and may cause abdominal cramping
Senna - Sennosides induce defecation by acting directly on the intestinal mucosa or nerve plexus, which stimulates peristaltic activity, increasing intestinal motility; senna usually produces its action 8-12 hours after administration
Sodium picosulfate

Osmotic laxatives

Small doses of osmotic agents are useful for long-term treatment of constipation with slow colonic transit in patients who are refractory to dietary fiber supplementation. In large doses, these agents may also be used as part of a bowel evacuation protocol for invasive procedures or surgery. Osmotic laxatives include the following:

Saline laxatives

Saline laxatives are used for acute treatment of constipation in the absence of bowel obstruction. These agents may also be used as part of a bowel evacuation protocol for invasive procedures or surgery. These agents increase peristaltic activity of the colon by promoting osmotic retention of fluid. Saline laxatives include the following:

Prokinetic agents

Prokinetic agents promote intestinal motility and are used for severe constipation-predominant symptoms associated with irritable bowel syndrome with constipation (IBS-C) or chronic idiopathic constipation (CIC).^[7]Prokinetic agents include the following:

Linaclotide - Guanylate cyclase C (GC-C) agonist that activates GC-C located on the luminal surface of intestinal epithelial cells; stimulation leads to increased cyclic guanosine monophosphate (cGMP), anion secretion, fluid secretion, and intestinal transit
Lubiprostone - Locally acting chloride channel activator that increases intestinal fluid secretion and intestinal motility; acts locally at apical portion of the intestine

Laxatives, other

See the list below:

Castor oil - Castor oil is reduced to ricinoleic acid; it decreases net absorption of fluid and electrolytes and stimulates peristalsis; acts on the small intestine